prepareSelectionQuery(DatabaseMapping sourceMapping,
org.eclipse.persistence.internal.sessions.AbstractSession session)
INTERNAL:
The selection queries are created by cloning the source mapping,
updating the necessary database fields on the mapping and then
initializing the mapping to create the internal selection query.

selectionQueriesForAllObjects

Selection queries from read all mappings will be cached and re-used.
E.G Entity A has a 1-M to Entity D (who has a subclass Entity E). We will
build a selection query to Entity E based on the selection query from the
1-M mapping from Entity A to Entity D.

prepareChildrenSelectionQuery

INTERNAL:
This method is called from individual mappings during their
initialization. If the mapping is to a class within a TABLE_PER_CLASS
inheritance hierarchy, what this method will do is prepare a selection
query to execute for every child descriptor in the hierarchy.
The selection queries are created by cloning the source mapping,
updating the necessary database fields on the mapping and then
initializing the mapping to create the internal selection query.
This query is then cached where needed using the source mapping's
selection query name as the key.

prepareSelectionQuery

INTERNAL:
The selection queries are created by cloning the source mapping,
updating the necessary database fields on the mapping and then
initializing the mapping to create the internal selection query.
This query is then cached where needed using the source mapping
as the key. A prepare is performed for each child of the hierarchy.